Automatic vehicle washes generally fall into broad categories. Drive-through vehicle washes in which a vehicle is conveyed or driven through the wash along a longitudinal conveyor and roll over vehicle washers in which the vehicle remains stationary and the wash apparatus moves relative to the vehicle. Roll over vehicle washes have the advantage that they are very compact and are relatively inexpensive. Drive-through vehicle washes take significantly greater longitudinal space and tend to be more expensive, both from the standpoint of the equipment cost as well as the building and real estate cost associated with the additional space requirements; however, speed and wash quality are typically superior.
A typical drive-through vehicle wash has an in-the-floor longitudinal conveyor such as that illustrated in U.S. Pat. No. 4,690,065, (Belanger, et al.), U.S. Pat. No. 4,715,287, (Wentworth, et al.) and U.S. Pat. No. 4,930,424, (Astley). As the vehicle is moved longitudinally by the conveyor, the vehicle is initially soaped with a soapy water mixture and moved into a wash station in which a series of cloth wheels and/or brushes wash the peripheral portions of the vehicle and an overhead cloth curtain or rotating wheel washes the upper side of the vehicle conventional washing apparatus of this type are illustrated in U.S. Pat. Nos. 4,057,866, (Belanger), U.S. Pat. No. 4,424,603, (Belanger, et al) and U.S. Pat. No. 4,530,126, (Belanger).
As illustrated in the preceding patents, wash equipment traditionally is modular in construction with a series of discreet washing devices longitudinally spaced along opposite sides of a conveyor. Once the vehicle leaves the wash region of the conveyor, it is rinsed and finally dried using a drying apparatus such as that illustrated in U.S. Pat. No. 4,817,301, Belanger, et al. Upon passing through the drying apparatus, the vehicle exits the conveyor. The speed with which the vehicle wash can process cars and trucks is dependent in large part upon the length of the wash station. To achieve a high quality wash, a certain level of wash time is necessary. To increase vehicle throughput, additional washing apparatus is needed to maintain sufficient wash quality.